1. Field of the Invention
The present invention relates to a holder device for holding a recording paper roll composed of a heat-sensitive recording paper, a photographic paper, or the like.
2. Background Arts
A photographic printer and a color thermal printer use a recording paper roll. The recording paper roll consists of a tubular spool shaft made of paper or plastic and a continuous recording paper wound thereon. The continuous recording paper is cut into a sheet of regulation-sized paper after printing.
A paper-feeding section of the printer is provided with a holder device of the recording paper roll. When the recording paper roll is set on the holder device, a pair of holders rotatably holds the recording paper roll. Each holder has a fitting portion which fits an inner surface of the spool shaft, and a rotational shaft. The recording paper roll is driven by a motor, for example, provided in the printer.
As a well-known drive system of the recording paper roll, there is a drive gear system in which a drive gear provided in one of holders rotates the spool shaft of the recording paper roll. This system, however, has a disadvantage in that if the holder loosely fits the spool shaft, the holder slips on the inner surface of the spool shaft, so that rotation of the holder is hardly transmitted to the recording paper roll.
In order to prevent a slip of the holder, there is an effective way in that a key groove is formed in the plastic spool shaft and a key provided in the holder is fitted therein. In a case where the paper spool shaft is used with environmental consciousness, however, it is impossible to form the key groove in terms of accuracy in molding.
To prevent a slip on the paper spool shaft, it is effective to provide claw members in the holder and engage the claw members with the inner surface of the spool shaft. In this case, the claw members have to be strongly biased toward the inner surface of the spool shaft. Thus, there is a disadvantage in that bias makes it difficult to attach the recording paper roll to the holder.